Need help with All-In-One OBD2 scan tool "Protocol Unknown" error

Hi guys,

A bit about the project -- I dropped a 1996 impala ss LT1/4l60e into my old Jaguar xj6 -- the car started up, but the tranny only went in reverse and 3/4th gear. I read up on trouble codes, and found that my PCM might be in "limp home mode", due to me not hooking up the O2 sensors.

I bought a cheapo elm327 USB cable off ebay -- could never get it to work with my laptop. It would have difficulty getting recognized by the computer, etc. I could get it to give me a 'Protocol unknown" error, when using a variety of scanning programs (ScanXL, ProScan, Scantool, etc). I assumed the cable was busted, and returned it.

Did some searching, found that the unit from "aldlcable.com" was the one to get, the All-in-one unit. Immidiately the unit was discovered by the computer, but, to my chagrin i got the same "protocol unknown" error when trying to patch into the car.

I checked the manual -- it appears as though i have the correct pins on the DLC in the jag. The protocol should be a very generic protocol, should it not? its just a GM PCM, very common.

Anyways, I don't know what to do. Has anyone had this error before? Has anyone had any luck in solving it? I'm at my wit's end here!